Oscillator apparatus and method with wide adjustable frequency range

Abstract

An oscillator formed from low cost discrete semiconductors and passive devices creates a linear periodic ramp of constant frequency with ramp slope based on an external voltage signal. Parameters are stable over a wide range of temperatures and variations of transistor parameters that normally degrade in extreme environments. The oscillator period can be phase and frequency synchronized to an external clock source over a wide range of frequencies. The oscillator ramp generator phase can be synchronized on a cycle by cycle basis for incorporation in power converters employing spread spectral EMI reduction techniques, multi-converter systems employing clock interleaving for distribution bus filter optimization, and resonant mode converters employing zero voltage switching techniques. Oscillator ramp rate is independent of frequency and can be synchronized to DC (inhibit) for use in ultra low power burst mode power conversion.

Description

BACKGROUND[0001]1. Technical Field[0002]This disclosure is generally related to oscillators, which may, for example, be employed in power converters and other devices.[0003]2. Description of the Related Art[0004]Power converters are used to transform electrical energy, for example converting between alternating current (AC) and direct current (DC), adjusting (e.g., stepping up, stepping down) voltage levels and / or frequency.[0005]Power converters take a large variety of forms. One of the most common forms is the switched-mode power converter or supply. Switched-mode power converters employ a switching regulator to efficiently convert voltage or current characteristics of electrical power. Switched-mode power converters typically employ a storage component (e.g., inductor, transformer, capacitor) and a switch that quickly switches between full ON and full OFF states, minimizing losses. Voltage regulation may be achieved by varying the ratio of ON to OFF time or duty cycle. Various to...

AI Technical Summary

Benefits of technology

This patent describes a method to generate a periodic ramp oscillator signal using a self-oscillating circuit that requires no start up input. The ramp's slope can be modulated by an external signal and is linear over a wide range of conditions. The output can be synchronized to an external clock signal input. Additionally, the method allows for synchronization up to the oscillator's self-oscillation frequency. This approach also uses less complex and lower cost components. Overall, this patent presents a simple, efficient way to generate a periodic ramp oscillator signal.

Problems solved by technology

In contrast, existing approaches utilize more costly and complex integrated circuit devices, such as comparators / operational amplifiers with additional components or a custom designed complex integrated circuit.

Existing approaches also appear to fail to operate over an ultra wide synchronous frequency range and temperature range as desired, with external slope modulation of the ramp oscillator signal.

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